Self-cleaning tiles and glasses for eco-efficient buildings

Self-cleaning and anti-bacterial activities of the photocatalyst titanium dioxide make it a superior compound for use in the ceramics and glass industry. Photocatalytic products have been on the market since 2001. Photocatalysis is a photochemical process that semiconductor materials such as titanium dioxide undergo when irradiated by light of a certain wavelength. A major drawback in commercializing conventional TiO₂ photocatalysts for ceramic applications is the large band gap of these materials which restricts its usefulness to outdoor environments. Titanium dioxide can only be activated upon irradiation with a photon of light <390nm in the ultraviolet region. Ultraviolet light makes up less than 5% of the solar spectrum, whereas the spectrum consists of ~40% visible light. Therefore, in order to utilize TiO₂ to its full potential and use it in an indoor environment, it is necessary to decrease the band gap size facilitating visible light absorption. In this chapter recent developments in the preparation of visible light activated catalysts are provided. A brief outline of various commercial photocatalytic tiles and glass products are listed. A general scientific mechanism of anti-bacterial action and self-cleaning activity of photocatalysts are also explained in detail. Finally, projected market growth, future trends and recommendations to improve the photocatalytic properties for the applications of tile and glass are described.